Hello,
I want to add region labels rather than markers.
Where is this plugin (Region labels in Silence Finder) ?
Are you wanting to label the regions that have sound, or the regions that have silence?
I want to label the regions that have silence 
You could modify the “Sound Finder” plug-in (SoundFinder.ny)
The main change that you need is line 165
Change:
((< val threshold)
to
((> val threshold)
How to get the plugin in the pictures ?
Do you have the plugin (silence-sound-marker.ny) ?
Where did you get that picture from?
The picture is somewhere on the audacity forum.
Can you send me the plugin even if it’s the development release ?
My guess is that it is available on the same page that you found the picture.
Try using the forum search (top right corner of the page).